Boyle’s Law: Definition, Formulas, Example Problems, and Benefits

Boyle’s Law – You must have known that when humans breathe, they will definitely inhale and exhale so that the volume of the lungs expands and contracts. Something that we inhale and exhale is air in the form of gas, aka we cannot see it with the naked eye, except when the weather is cold. Even though the presence of this gas cannot be seen with the naked eye, it can be calculated using a chemical formula, to be precise by adhering to the working principle of Boyle’s Law.

Boyle’s law is a part of chemistry which turns out to have many uses in our daily lives. In addition to the respiratory system of living things, it turns out that Boyle’s Law is also often applied to the tools around us. Then, how does Boyle’s Law sound? How does Boyle’s law apply to everyday life? Let’s look at the following reviews so that You understands these things!

How Does Boyle’s Law Sound?

As with other chemical laws, Boyle’s law also has a sound statement coined by its creator, namely Robert Boyle in 1662. Boyle’s law states that “in a closed room, the volume of a mass of gas will change inversely with pressure, when the temperature is constant” . Yep, Boyle’s law becomes one of the laws of chemistry and becomes an ideal chemical law. In this law, describes the existence of an inverse proportional relationship between absolute pressure and air volume, especially when the temperature remains constant in a closed system.

Boyle’s law is named after its discoverer, namely Robert Boyle, a chemist and physicist in 1662. At that time, Robert Boyle stated that ” For a fixed amount of ideal gas at the same temperature, P (pressure) and V (volume) are inversely proportional (where one doubles, the other half).” Well, in this case, what is called an ideal gas is a gas that meets the following assumptions:

  • It consists of a large number of particles and there is no force of attraction between the particles.
  • Each gas particle will always move in a random direction.
  • The particle size is negligible in relation to the size of the container.
  • Each collision that occurs is perfectly elastic.
  • The gas particles are evenly distributed throughout the space in the container.
  • The motion of gas particles will obey Newton’s laws of motion.

Robert Boyle also argued about the nature of gases, namely that the mass of the gas (zero amount) and the temperature of a gas must be kept constant, while the volume of the gas will be changed. While the pressure released by the gas will also change in such a way that there is a multiplication between pressure (P) and volume (V), always close to constant. Thus, that is the condition in which the gas becomes a perfect (ideal) gas.

The existence of Boyle’s Law cannot be separated from the experimental efforts that have been carried out many times. The relationship between pressure and volume was first put forward by amateur scientists, namely Richard Townley and Henry Power, which was then continued by Robert Boyle. When he wanted to “create” Boyle’s Law, Robert conducted an experiment with air, where he considered fluid particles in the middle of an invisible spring. At that time, air was still seen as one of the four elements, but Robert disagreed, so he did further research until he succeeded in publishing Boyle’s Law in 1662.

After that, a French physicist named Edme Mariotte appeared, who also discovered the same law but separately, in 1676 to be precise. Since this law was published by Robert Boyle, it is called the Boyle-Mariotte Law.

Boyle’s Law formula

The Basic Theory of Boyle’s Law

The existence of Boyle’s Law uses a theoretical basis in the form of “at a constant temperature, the pressure (P) of an ideal gas is inversely proportional to the volume of the gas (V), or PV = C (C is a constant)” . So it becomes the following.

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Information:

Pu = room air pressure

Pk = air pressure in the air column

t = height of the air column

h = difference in height of the mercury surface

Boyle’s Law formula

The formula regarding Boyle’s Law was put forward by Robert Boyle which stated that the product of pressure (P) and volume (V) will be constant, as long as the mass and temperature of the gas are maintained consistently. Mathematically, the formula is written:

P x V = constant

P = gas pressure (N/ m²)

V = gas volume (mз)

Boyle’s Law Equation

In order for the gas and the two states to be in balance, especially at a constant temperature, the equation becomes:

P₁. V₁ = P₂. V₂ = …… = Pₙ. Vₙ

Information:

P₁ = Initial pressure of the gas in the chamber (Nm² or Pa)

V₁ = The initial volume of gas in the chamber (m3)

P₂ = Final pressure in chamber (Nm² or Pa)

V₂ = Final volume in space (m3)

Please note , You , to measure the gas pressure in a confined space, you can use a tool called a manometer. Here is the shape of the manometer:

Problems and Discussion of Boyle’s Law

Example Question 1

It is known that the amount of an ideal gas has a pressure of P and a volume of V. Then, the gas pressure rises and changes to 2 times the initial pressure. What is the volume of the gas now?

Discussion:

P₁ V₁ = P₂ V₂

P x V = 2P. V2

V = 2 . V2

½ V = V2

So, the gas volume is now ½ of the initial gas volume.

Application of Boyle’s Law in Human Life

The existence of Boyle’s Law certainly provides many benefits for everyday human life. Even indirectly, it actually affects the respiratory system of living things on this earth. What are the applications of Boyle’s Law in our lives? Let’s look at the following description!

1. Respiratory System of Living Things

Especially in the human respiratory system, during the respiration process, our lungs apply the working principle of Boyle’s Law. When inhaling air, the lungs will of course be filled with air, therefore they will expand. Lung volume will increase as the pressure level decreases. Likewise, when the lungs expel air, the lungs will shrink so that the volume decreases and the pressure increases. Changes in pressure and volume in the lungs are only temporary and periodic .

2. Bottles of Soda

Does You often drink soda from a bottle? Well, the existence of a soda bottle is a form of application of Boyle’s Law, you know… A soda bottle containing a mixture of carbon dioxide has a lid that closes tightly. This is because there are air molecules in the tightly packed container, causing the air to have no room to move.

When the bottle is opened, there will be a hissing sound and some air molecules will come out. Thus it will provide space for the movement of air molecules. This is where the change in pressure occurs according to changes in volume. Usually, when we shake the soda bottle, after opening the lid, the soda will expand and even spill onto our hands. This happens because the gas in the bottle is trying to get out and mixed into the fluid, so that when the gas is released it will emit a foamy liquid. The pressure inside the bottle goes down, while the gas volume goes up.

3. Use of Syringes

Syringes, which are often used as medical equipment, also use the working principle of Boyle’s law. In a syringe it consists of a cylinder that functions to collect fluid and a pusher to vary pressure. When the plunger is pressed, the fluid volume will decrease so that the pressure will increase. Likewise, when we pull the plunger, the volume will be increased while the pressure is reduced.

4. Spray Paint

Does You often see people using spray paint, when they are doing graffiti on the wall maybe? Spray paint also works with the principle of Boyle’s Law, you know… Although there are several types of aerosol cans in spray paint, basically all of them still use the working principle of Boyle’s Law.

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Usually, before we want to spray the spray paint, we are required to shake the can so that the substance in the can can spread. There are two substances in the can of spray paint, namely the paint product itself and a gas that is pressurized to each other in the form of a liquid. Well, this liquefied gas has a boiling point far below room temperature. That’s why cans of spray paint need to be tightly sealed, so the gas doesn’t boil away.

After pressing on the spray paint or pressing the nozzle, it will press the paint inside the can. Under the high pressure, the paint will be “forced” out of the nozzle.

5. Astronaut Suits in Space

You must have known that in outer space there is no air or atmosphere, that’s why it’s called a vacuum. If you adhere to the working principle of Boyle’s Law, when the gas is under pressure it will enter the vacuum region, then it will expand without limit. This is then applied to the special clothes of astronauts who are going to outer space. If the special suit breaks, of course it will have fatal consequences for the astronaut in the form of boiling blood and liquid and cause him serious injury.

6. Scuba Diving Activities

Scuba diving, which involves diving under water, cannot be separated from the existence of Boyle’s law. When scuba diving divers want to dive, they are required to balance the relationship between volume and pressure so that they don’t feel sick or even injured. Of course this can happen because when we enter or approach water to a certain depth, our bodies will experience high pressure.

This high pressure affects the increased solubility of gases in the blood. Therefore, the diver must immediately ascend if the pressure is too high, but accompanied by a slow speed so as to minimize any injury.

Get to know the Gay Lussac Law

The existence of Gay Lussac’s Law turns out to be very closely related to Boyle’s Law, you know… Basically, Gay Lussac’s Law is a law of volume ratios. Yep, in general, the mixed gases will not show reaction symptoms. However, if given special treatment and conditions, it is likely to cause a reaction. For example, when there is a mixture of O2 gas with H2 it will not produce any reaction, but if it is mixed with an electric spark it will definitely form a reaction. This chemical law was created by a French chemist named Joseph Louis Gay-Lussac who has made a series of quantitative measurements of the volume of the gases involved in the reaction.

Since Gay Lussac’s Law talks about the relationship between gas volume and gas temperature at the same pressure, the law reads: “The volume of a gas is proportional to its temperature, as long as the pressure remains constant.”

When written in equation form, the formula becomes:

V/ T = constant

V₁ / T₁ = V2 / T2

Information:

V = Volumes

T = Temperature

Boyle-Gay Lussac law

Actually, Boyle-Gay Lussac’s Law is a synthesis of Boyle’s Law and Gay Lussac’s Law, so that the two formulas can be put together to become:

P x V / T = constant, or

P₁ x V₁ / T₁ = P2 x V2 x T2

Meanwhile, under ideal conditions, the ideal gas equation according to Boyle-Gay Lussac’s Law becomes:

P. V = N . k . Q

Information

k = Boltzmann’s constant

N = number of gas particles

General Ideal Gas Equation

Meanwhile, there is also a general ideal gas equation based on Boyle’s Law and Lussac’s Gas Law, with the formula in the form of:

p.m. V = nRT

Information:

p = gas pressure

V = gas volume

n = number of gas particles

R = gas constant

T = gas temperature (K)

Then, if you want to find the number of moles or gas particles, you can use the formula in the form of:

N = m/M = gr/Mr

Information:

N = number of gas particles

m = total mass of gas

M = relative molecular mass of the particle

Well, that’s a review of what Boyle’s Law is and its application to everyday human life. Does You understand how spray paint works?